Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

049
FXUS63 KLOT 240018
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
718 PM CDT Thu Apr 23 2026

.KEY MESSAGES...

- Period of showers and scattered thunderstorms with a cold
  front tonight into Friday.

- Seasonable and dry conditions over the weekend.

- Threat of showers and thunderstorm return Monday, as does the
  threat of severe weather and heavy rainfall.

&&

.DISCUSSION...
Issued at 224 PM CDT Thu Apr 23 2026

All is quiet across our region this afternoon. However, well
west of our area (across the Mid-Missouri Valley) a line of
thunderstorms will continue to develop and mature in advance of
an eastward shifting cold front through the remainder of the
afternoon. The airmass in which these storms develop will favor
organized severe thunderstorms into this evening with eastward
extent across much of IA southwestward into eastern KS and
western MO. Fortunately, this line of storms is expected to
weaken with eastward extent tonight as nocturnal stabilization
of the boundary layer occurs overnight. Accordingly, it appears
the severe threat will be fairly low across much of northern IL
into northwestern IN. However, lingering outflow from this line
of decaying line of storms could still produce a brief period of
gusty winds up to 50 mph, particularly west of the Fox Valley
and Illinois River Valley. Rainfall rates and amounts are also
expected to be waning with this activity overnight, so we
currently do not anticipate any worsening of the ongoing river
flooding.

Lightning and thunder activity will be on a diminishing trend
into early Friday morning as the remnant showers shift across
northeastern IL and northwestern IN in advance of the
approaching cold front. While extensive cloud cover through the
morning will limit destabilization in advance of this front,
cooling mid-level temperatures associated with the incoming mid-
level short-wave does look to support steepening low-to-mid
level lapse rates by midday/early afternoon. Accordingly, it
appears some renewed widely scattered showers and storms will
occur with, and just ahead of, the cold front into early Friday
afternoon. The most favored areas for this new development looks
to be generally along and east of the I-55 corridor.
Fortunately, limited instability and shear looks to curtail the
threat for more organized severe storms. Otherwise, expect the
threat of showers and storms to end from northwest to southeast
through the afternoon.

Cooler, but pleasant weather conditions are expected through
the weekend in the wake of Friday`s cold frontal passage. Expect
inland temperatures to range from the upper 60s to low 70s.
However, closer to Lake Michigan, onshore east-northeasterly
winds will keep conditions cooler, with highs generally in the
50s to low 60s.

Following a quiet weekend weather wise in our neck of the
woods, a significant mid-level impulse (and upper-level speed
max) coming onshore across southern CA late Saturday, is
forecast to eject east-northeastward across the Rockies by late
Sunday. This will set the stage for lee cyclogenesis and the
development of a northeastward tracking notable sub-995 mb low
from the central Plains somewhere up across the upper Midwest
into early next week. While ensemble spread with the exact
surface low track across the Upper Midwest on Monday remains,
conceptually a strong surface low tracking northwest of area
during the afternoon and evening hours in late April certainly
adds increased concern for the threat of severe weather and
heavy rainfall in or very near our area. Accordingly, Monday
will be a day we will have to watch closely for both a heavy
rain and a severe weather threat.

In the wake of the Monday system, a period of cooler and drier
weather should set up for the middle of next week.

KJB

&&

.AVIATION /00Z TAFS THROUGH 06Z SATURDAY/...
Issued at 718 PM CDT Thu Apr 23 2026

Key Messages:

- Low-level wind shear is possible at times tonight.

- There remains a 30-50% chance for thunderstorms tonight,
  highest chances at RFD.

- Additional showery periods are possible during the daytime
  tomorrow.

- MVFR ceilings are likely tomorrow morning.


A low-level jet stationed over the area will strengthen to
around 40-45 kts at 2000 ft AGL this evening. Marginal low-
level wind shear may thus be observed for a period of time
tonight wherever gusts cease and sustained winds subside under
10 kts (most likely at GYY, DPA, and RFD).

A line of storms will approach the area from the west later
tonight, though it will be on a weakening trend. RFD stands the
best chance to see lightning and could also see a brief period
of showers a few hours before the main line of decaying storms
arrives. For the Chicago metro terminals, the overall chances
for lightning are lower than at RFD, but still appear to be
appropriately conveyed by the inherited PROB30 groups for TSRA
in the respective TAFs. Despite being in a decaying state, the
incoming line of convection may still produce a gusty westerly
wind shift and gusts in the 30-40 kt range as it rolls through
the area. Shower coverage should then diminish towards
daybreak, though at least isolated showers will remain possible
through the morning hours while MVFR ceilings likely filter into
the area.

Isolated to scattered showers may redevelop closer to an
incoming cold front during the afternoon tomorrow. Questions
about the quality of available low-level moisture and the degree
of diurnal destabilization with the morning cloud cover remain,
but there appears to be enough support in high-resolution model
guidance to at least warrant a PROB30 group for SHRA at all of
our TAF sites. In the worst case, a few isolated thunderstorms
may develop in the advertised PROB30 windows, but did not have
enough confidence in TSRA occurring to warrant a formal mention
of that in the TAFs at this time. The shower/storm potential
should end and winds will shift to a northwesterly direction
behind the cold front after it moves through tomorrow afternoon.

Ogorek

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

$$

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